Function Problems

[dmeta10]

So I'm trying to make a BAC table. But the problem is the math isn't coming back right. Like it just keeps saying 0.00 and nothing else. But that isn't right.

void computeBloodAlcoholConcentration(int numDrinks, int weight,
	int duration, double &maleBAC, double &femaleBAC)
{
	// to get the right .01 value
	double y = ((duration / 40.0) * 0.100000);


	double x = (numDrinks / weight);
	femaleBAC = (x * 4.5);
	maleBAC = (x * 3.8);

	//so i only get two decimal points
	std::cout.precision(2);
	if (x == 0.00)
	{
		cout << numDrinks << " " << std::fixed << femaleBAC - y << " " << "Safe to Drive" << endl;
		cout << numDrinks << " " << std::fixed << maleBAC - y << " " << "Safe to Drive" << endl;
	}

It's a lot bigger than this, but I don't think I need all of it to fix the problem.
Any help would be great. Thanks!!

[TarikNeaj]

Probably because of integer division. You don't want integer division. Change

from double y = ((duration / 40) * 0.100000);
to - double y = ((duration / 40.0) * 0.100000); // note 40.0

[dmeta10]

I changed it to 40.0 like you said and it still says 0.00 .

[cire]

Note that you also have integer division on line 8.

[dmeta10]

So how do i fix that so that it goes back to floating point?

[cire]

Cast one of the variables to double.

[dmeta10]

Okay that works but is there another way? I need to keep them both as int by the rules of the program I'm doing. (I don't really know why it is restricted to that ) but the program that needs to check my answer is not happy with that way of it working

[cire]

Okay that works but is there another way?

If you want floating point arithmetic, one must involve floating point types.


[quote](I don't really know why it is restricted to that ) but the program that needs to check my answer is not happy with that way of it working [/quoe]
I didn't way to change the type. I said to cast the variable to double.

double x = ((double)numDrinks / weight);

Or the wordier C++ cast:

double x = (static_cast<double>(numDrinks) / weight);

[dmeta10]

yay ! that works! lol Thank you

now its not doing the subtraction part for that y. So do I change that to where I get the variables for femaleBAC and maleBAC, or do I put that math somewhere else. The constant is -.01 for every 40 minutes.